Considerable effort has recently been directed towards thin film transistors (TFTs) with organic active layer. See, for instance, F. Garnier et al., Science, Vol. 265, p. 1684. Among the organic compounds that are currently most frequently considered for use as active layer material is .alpha.-hexathienyl, frequently referred to as .alpha.-6T. As shown, for instance, F. Garnier et al., such TFT comprises an organic active layer in contact with spaced apart source and drain electrodes, and spaced from a gate electrode. See, for instance, G. Horowitz, J. Applied Physics, Vol. 70(1), p. 469.
However, despite considerable research and development effort, "organic" TFTs have not yet reached commercialization, at least in part due to relatively poor device characteristics of typical prior art devices. It is generally believed that the poor device characteristics are at least in part due to the relatively low quality of typical organic active layers.
A recent significant improvement in device characteristics resulted from a change in device structure. See co-assigned U.S. patent application Ser. No. 08/353,024, filed Dec. 9, 1994 by A. Dodabalapur et al.
A further recent significant advance resulted from the discovery of an improved method of making organic compounds that are useful as active layer material. See co-assigned U.S. patent application Ser. No. 08/353,032, filed Dec. 9, 1994 by A. Dodabalapur et al. Using the novel synthesis method the inventors of the '032 application were able to make films of .alpha.-6T that had room temperature conductivity substantially below 10.sup.-8 S/cm, and TFTs that comprise the improved .alpha.-6T had on/off ratios greater 10.sup.6. As is conventional, the .alpha.-6T layer was formed by sublimation. The above referenced two patent applications and the Garnier et al. article are incorporated herein by reference.
Despite the recent advances, it would still be of considerable interest to have available .alpha.-6T of still higher quality, since such improvement is likely to translate into improved device characteristic. This application discloses a novel form of -6T which, on theoretical grounds, is believed to be, inter alia, a promising active layer material for organic TFTs.